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<h2><span class="refentrytitle">Struct template otherwise</span></h2>
<p>boost::proto::otherwise &#8212; 
          Syntactic sugar for <code class="computeroutput"><a class="link" href="when.html" title="Struct template when">proto::when</a>&lt; <a class="link" href="_.html" title="Struct _">proto::_</a>, Fun &gt;</code>,
          for use in grammars to handle all the cases not yet handled.
        </p>
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<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../proto/reference.html#header.boost.proto.transform.when_hpp" title="Header &lt;boost/proto/transform/when.hpp&gt;">boost/proto/transform/when.hpp</a>&gt;

</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Fun<span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="otherwise.html" title="Struct template otherwise">otherwise</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="when.html" title="Struct template when">proto::when</a>&lt; <a class="link" href="_.html" title="Struct _">proto::_</a>, Fun &gt; <span class="special">{</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idp144984464"></a><h2>Description</h2>
<p>
            Use <code class="computeroutput">proto::otherwise&lt;T&gt;</code> in your grammars as a synonym for
            <code class="computeroutput"><a class="link" href="when.html" title="Struct template when">proto::when</a>&lt; <a class="link" href="_.html" title="Struct _">proto::_</a>, Fun &gt;</code>
            as in the following transform which counts the number of terminals in an expression.
          </p>
<p>
            </p>
<pre class="programlisting"><span class="comment">// Count the terminals in an expression tree.</span>
<span class="comment">// Must be invoked with initial state == mpl::int_&lt;0&gt;().</span>
<span class="keyword">struct</span> <span class="identifier">CountLeaves</span> <span class="special">:</span>
  <a class="link" href="or_.html" title="Struct template or_">proto::or_</a><span class="special">&lt;</span>
    <span class="identifier">proto</span><span class="special">::</span><span class="identifier">when</span><span class="special">&lt;</span><a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special">&lt;</span><a class="link" href="_.html" title="Struct _">proto::_</a><span class="special">&gt;</span><span class="special">,</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">next</span><span class="special">&lt;</span><a class="link" href="_state.html" title="Struct _state">proto::_state</a><span class="special">&gt;</span><span class="special">(</span><span class="special">)</span><span class="special">&gt;</span><span class="special">,</span>
    <span class="identifier">proto</span><span class="special">::</span><span class="identifier">otherwise</span><span class="special">&lt;</span><a class="link" href="fold.html" title="Struct template fold">proto::fold</a><span class="special">&lt;</span><a class="link" href="_.html" title="Struct _">proto::_</a><span class="special">,</span> <a class="link" href="_state.html" title="Struct _state">proto::_state</a><span class="special">,</span> <span class="identifier">CountLeaves</span><span class="special">&gt;</span> <span class="special">&gt;</span>
  <span class="special">&gt;</span>
<span class="special">{</span><span class="special">}</span><span class="special">;</span></pre>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2008 Eric Niebler<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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